cow-2022-31

CASE OF THE WEEK

Editor: Mahmut Akgul (akgulm@amc.edu)

2022-31/August 8

Contributors: Daniel Athanazio, Paulo Roberto Fontes Athanazio

A woman in her 80s underwent nephrectomy along resection of multiple retroperitoneal nodules. One small nodule (1.5 cm) showed a firm and fascicular cut surface (see figures 4 and 5).

CLICK ON THE BELOW THUMBNAILS TO ENLARGE PHOTOS.

Quiz

a) Well-differentiated liposarcoma – adipocytic and sclerosing subtypes

b) Pleomorphic lipoma

c) Fibromatosis

d) Myxoid liposarcoma

e) Low-grade dedifferentiated liposarcoma

Well-differentiated liposarcoma – adipocytic and sclerosing subtypes

Well differentiated liposarcoma is subdivided morphologically into three main subtypes: adipocytic (lipoma-like), sclerosing, and inflammatory. Combination of patterns are common, particularly in retroperitoneal liposarcomas. The lipoma-like subtype is the most common and predominated in the present case. It shows predominance of mature adipocytes although there is a substantial variation in size of these cells. Usually, nuclear atypia in adipocytes or stromal spindle cells is obvious. The sclerosing subtype is the second most common and is often observed in retroperitoneum and spermatic cord. Bizarre stromal cells are seen in a collagenous stroma and the adipocytic component may be obscured. The small nodule (1.5 cm) had findings consistent with sclerosing liposarcoma.

Dedifferentiated liposarcoma has been defined by the presence of high-grade morphology. However, it has been increasingly recognized cases of low-grade dedifferentiation. Such areas have increased cellularity and proliferation of fusiform cells with mild atypia, often organized in fascicular pattern. In the present case, the small white nodule was interpreted as a separate nodule of sclerosing subtype of well differentiated liposarcoma. No areas of abrupt or gradual transition from lipoma-like areas and spindle cell areas were observed within this nodule.

1. Thway K. Well-differentiated liposarcoma and dedifferentiated liposarcoma: An updated review. Semin Diagn Pathol. 2019 Mar;36(2):112-121.

2. The WHO Classification of Tumours Editorial Board. WHO Classification of Tumours Soft Tissue and Bone Tumours, 5th ed. Lyon: IARC Press; 2020.

Daniel Athanazio
Imagepat, Laboratory of Pathology
Federal University of Bahia / Hospital Universitário Professor Edgard Santos Salvador
Bahia, Brazil

Paulo Roberto Fontes Athanazio
Imagepat, Laboratory of Pathology
Salvador, Bahia, Brazil

Retroperitoneum

Liposarcoma; Retroperitoneum; Kidney